Hydraulic Oil in chaincase

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F0urR!ng$

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Hello, I am new to the skid steer thing. I bought a Bobcat 743, runs great and the engine is perfect. There were some oil leaks and play in the axles so I had to replace the bearings and oil seals. When we opened the chaincase cover it was full with milky oil to the top. According to the mechanic, it was required to change the quad seals of the drive motors. The next day the skid steer was used for about 2 hours until a growling noise came up when turning right. The mechanic suspected that the chain might be loose so we reopened the chaincase cover and there was hydraulic oil in the case. According to the mechanic the drive motor seals should be replaced as they are not holding oil pressure. Please advice Thank you!
 

farmshop

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If the case filled with oil that quick the seal is probably leaking on the drive motor
 
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F0urR!ng$

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If the case filled with oil that quick the seal is probably leaking on the drive motor
Thank you for your reply The mechanic pulled the drive motor. He plugged the main oil inputs and tried to spin the shaft with his hand. The shaft was turning and the residue oil in the motor was not spitting from return line, instead it was spitting from one of the plugged lines. According to the mechanic this should not happen and the seals should be replaced. Is this true?
 
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F0urR!ng$

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Thank you for your reply The mechanic pulled the drive motor. He plugged the main oil inputs and tried to spin the shaft with his hand. The shaft was turning and the residue oil in the motor was not spitting from return line, instead it was spitting from one of the plugged lines. According to the mechanic this should not happen and the seals should be replaced. Is this true?
An update, I just checked the hydraulic oil level in the reservoir and it has dropped by approx 1 inch over night without even running the machine.
 

farmshop

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An update, I just checked the hydraulic oil level in the reservoir and it has dropped by approx 1 inch over night without even running the machine.
Unless there is a axle shaft seal leaking that is weird. I wouldn't think it would pull oil from the case. At this point with the motor removed I would probably find a hydraulic repair place to look at the motor or see if someone like loader parts source has a reman you can swap. I don't know how scientific his tests are. If you plug a fitting with the correct plug it shouldn't leak. I wouldn't try too hard to spin the motor with the ports plugged I wouldn't want to damage seals
 
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Unless there is a axle shaft seal leaking that is weird. I wouldn't think it would pull oil from the case. At this point with the motor removed I would probably find a hydraulic repair place to look at the motor or see if someone like loader parts source has a reman you can swap. I don't know how scientific his tests are. If you plug a fitting with the correct plug it shouldn't leak. I wouldn't try too hard to spin the motor with the ports plugged I wouldn't want to damage seals
All of the remaining hydraulic oil in the reservoir are in the chain case now. Is it possible that the seal between the drive motor and the gear reduction is not good?
 
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All of the remaining hydraulic oil in the reservoir are in the chain case now. Is it possible that the seal between the drive motor and the gear reduction is not good?
Also I would like to ask again about the growling noise...is it true that the chain might be loose?
 

farmshop

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Also I would like to ask again about the growling noise...is it true that the chain might be loose?
Chain could be loose. I would jack up each wheel and check for excessive movement. If the hydraulic oil is going in the chain case you have a bad seal in a motor. Usually if a motor leaks that much oil the whole thing needs to be rebuilt not just the output seal
 
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Chain could be loose. I would jack up each wheel and check for excessive movement. If the hydraulic oil is going in the chain case you have a bad seal in a motor. Usually if a motor leaks that much oil the whole thing needs to be rebuilt not just the output seal
No excessive movement in the wheels since all the bearings have been recently replaced. Turns out the plastic guide is loose. I think this mechanic doesn't know much lol Regarding oil leaks I have been reading some forums and it says that the motor can't be rebuilt so can you please specify what seals should be replaced and how many are they?
 

mmsllc

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No excessive movement in the wheels since all the bearings have been recently replaced. Turns out the plastic guide is loose. I think this mechanic doesn't know much lol Regarding oil leaks I have been reading some forums and it says that the motor can't be rebuilt so can you please specify what seals should be replaced and how many are they?
I would suggest replacing the chain drive lube. Any time you find milky (water contaminated) fluid, it is always best to remove as much of it as possible. It does sounds as if one or both drive motors are leaking past the shaft seals. I would suggest replacing both seals or motors, if it has come to that point where they can not be rebuilt. Working on these machines is pretty hard to schedule & time perfectly with the needed cash, but I'd play it safe with my money making machine, if I was in your place.
 

farmshop

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I would suggest replacing the chain drive lube. Any time you find milky (water contaminated) fluid, it is always best to remove as much of it as possible. It does sounds as if one or both drive motors are leaking past the shaft seals. I would suggest replacing both seals or motors, if it has come to that point where they can not be rebuilt. Working on these machines is pretty hard to schedule & time perfectly with the needed cash, but I'd play it safe with my money making machine, if I was in your place.
Most drive motors can be repaired it is just a matter of time and money. Most people don't want down time so they order a replacement. Many repair shops are just happy swapping over priced parts.
 
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Most drive motors can be repaired it is just a matter of time and money. Most people don't want down time so they order a replacement. Many repair shops are just happy swapping over priced parts.
Thank you for your replies! I have replaced the seals of the gear reduction and no more leaks! I changed the oil in the chaincase also. The machine is running great and perfect.
 
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